The present invention relates to the preparation of collagen-coated foodstufs, especially sausages.
There are two approaches to making sausages. The first is to take natural or artificial sausage casing and stuff it with sausage meat. In recent times, it has become known to coextrude a strand of sausage material which has an inner core of meat emulsion having an outer surface material that can be coagulated to provide an encasement for the strand. The outer surface material may consist of a gel with a collagen protein. The coagulation normally includes subjecting the extruded strand to a brine (salt) solution. Coagulation as used herein refers to the step of hardening and stabilization of the casing. This is principally done in two ways; firstly by removal of water from the collagen gel, and secondly by crosslinking the collagen fibers.
It is known that collagen is a protein able to form aqueous gels of high water content. Typically maximum gel water uptakes can be achieved at a pH around 2, and therefore, although technically a high pH is also possible (around 13), most extrusion gels contain acidified collagen fibers. In the generally known methods, the water content of the gel coating is lowered with the assistance of osmosis by leading the strand of foodstuffs through a concentrated salt bath. Said brine is preferably of a pH higher than the pH of the gel, preferably &gt;pH=7, to lower the water binding ability of the gel, and thus facilitate the osmotic drying. The brine may include any type of suitable food approved salt. The brine may also contain other functional ingredients such as crosslinking agents, plasticizing agents or fibrous or other coating materials. A typical sausage coextrusion process is described in U.S. Pat. No. 3,622,353, Bradly, et al. In practice this process includes the steps of coextruding a substantially uniform layer of collagen gel around an extruded edible product, whereby the collagen is coagulated by passing the extruded strand of foodstuff through a brine bath and successively air drying the casing. Said brine bath typically contains a concentrated solution of sodium chloride, and consists of a shallow trough, through which a conveyor belt transports the coextruded strand. Optionally, the brine treatment includes spraying the brine onto the sausage surface. Typical brine contact times in the past are 1.5-5 seconds.
In more recent times, sausage coextrusion methods involve a prolonged brine contact period. These methods achieve a better coagulation to create a stronger casing. In these processes, brine contact lasts 30-300 seconds.
The longer contact times of the brine presents certain problems. First of all, the organoleptical properties of the sausage and casing such as taste, color, transparency are negatively influenced. It is therefore necessary to limit the brine contact time in order not to deteriorate the sausage quality. Low taste salts as sodium carbonate are therefore used, but still side effects are occurring and are difficult to maintain at an acceptable level.
The fact that salt remains on the sausage surface after leaving the brine bath increases these problems. When the sausage is thereafter air dried, salt crystals form on the sausage surface, giving an unwanted salty appearance and deteriorating the transparency of the casing. Also, taste is negatively influenced, as is the color of the meat.
A further problem with salt being "lost" in the production is the costs thereof. Recently used salt types are far more expensive than the customary sodium chloride. Salt loss has therefore become an important factor in overall production costs of the sausage. An even further disadvantage of the residual brine is that the overall mineral content of the sausage product is raised, which can go beyond the maximum levels set by governmental regulations.
It is therefore a principal object of the present invention to provide a method for manufacturing coextruded food strands with an edible casing in which the previous problems and disadvantages of the known coextrusion methods do not occur.
It is a further object of the present invention to provide a novel method for reducing unwanted organoleptical effects of a brine treatment on a coextruded food product.
It is still a further object of the present invention to provide a method for substantially reducing residual brine left on the surface of coextruded food strands.
It is yet a further object of the present invention to provide a method of coagulating collagen containing gel in the coextrusion process whereby the brine costs are substantially reduced.
It is yet a further object of the present invention to provide a method of coagulating collagen containing gel to achieve a better coagulation through higher brine residence times, without negatively influencing the organolptical properties of the food product.
It is still a further object to the present invention to provide a means for removal of surface attached brine from a coagulated collagen coated coextruded foodstuff.
An additional object of the present invention is to create by coextrusion a substantially uniform layer of a collagen-containing gel around an elongated strand of foodstuff, coagulating said foodstuff by contacting it with a salt-containing brine, removing residual brine left on the surface of said foodstuff after said contact with the brine, and recirculating the removed brine for reuse.
These and other objects will become clear from the following description of the invention.